Bobbin thread replenishing mechanism for sewing machines



5. J. KETTERER BOBBIE THREAD REPLENISH'ING MECHANISM FOR SEWING MACHINES Filed Aug. 29, 1966 Oct. 29,1968

6 Sheets-Sheet l f mw T e N a! M. MK

BY a E fiTTORNEY WITNESS 1 Oct.29, 1968 KETTERER BOBBIN THREAD REPLENISHING MECHANISM FOR SEWING MACHINES Filed Aug. 29, 1966 6 Shee ts-Sheet 2 Stanley J Kerferer BY 2 z Z TORNEY Oct. 29; 1968 5. J. KETTERER 3,407,760

BOBBIN THREAD REPLENISHING MECHANISM FOR SEWING MACHINES Filed Aug. 29, 1966 6 Sheets-Sheet 5 1 INVENTOR. Stanley J. Kefferer WITNESS BY b3! 2370M Oct. 29, 1968 5. J. KETTERER 3,407,760

BOBBIH THREAD REPLENISHING MECHANISM FOR SEWING MACHINES Filed Aug. 29, 1966 6 Sheets-Sheet 4 INVENTOR.

Stanley J. Kefferer wrmsss Y W 2%" Q-LI-K/ ATTORNEY Oct. 29, 1968 S. J. KETTERER BOBBIN THREAD REPLENISHING MECHANISM FOR SEWING MACHINES Filed Aug. 29, 1966 WITNESS 6 ShegtS-Sheet 5 LFi l5.

INVENTOR.

; BY Stanley J Keflerer TORNEY Oct. 29, 1968 5, KETTERER 3,407,760

BOBBIN THREAD REPLENISHING MECHANISM FOR SEWING MACHINES Filed Aug. 29, 1 966 e SheetsSheet 6 INVENTOR.

Stanley J. Keflerer TORNE Y United States Patent 3,407,760 BOBBIN THREAD REPLENISHING MECHANISM FOR SEWING MACHINES Stanley J. Ketterer, Morris Plains, N.J., assignor to The Singer Company, New York, N.Y., a corporation of New Jersey Filed Aug. 29, 1966, Ser. No. 575,594 14 Claims. (Cl. 112-184) ABSTRACT OF THE DISCLOSURE A loop taker for a lockstitch sewing machine is disclosed together with a mechanism for replenishing thread on the bobbin in place in the loop taker from the needle thread supply. Means are provided whereby the loop taker manipulates replenishment thread in a novel manner onto the bobbin and the bobbin is rotated in a direction opposite that of loop taker movement so that the replenishment thread will be introduced quickly and effectively to the influence of a bobbin thread tensioning spring on the bobbin case and thence to the bobbin.

This invention relates to lockstitch sewing machines, and more particularly to a novel and improved mechanism for replenishing thread on a bobbin in place in the loop taker.

The principle of replenishing thread on a bobbin in place in a loop taker during movement of the sewing machine needle and loop taker as is required for the formation of lock stitches is shown in prior patents such as the United States Patent No. 3,115,855, Dec. 31, 1963, to which reference may be had for disclosure of a typical construction in which thread is wound directly on the bobbin and bobbin thread tension during subsequent sewing, is applied by the application of frictional resistance to turning of the bobbin. While the absence of bobbin thread tensioning springs or the like in the construction of United States Patent No. 3,115,855 facilitates introduction of thread to the bobbin during replenishment, the derivation of bobbin thread tension during subsequent sewing by frictional resistance to rotation of the bobbin makes it difficult to produce consistent stitching because the bobbin thread tension will vary from full to empty bobbin.

It is an object of this invention to provide a mechanism capable of replenishing thread on a bobbin of a lockstitch sewing machine in a novel manner through a bobbin thread tensioning spring.

A prior United States Patent No. 3,063,392, Nov. 13, 1962, discloses a bobbin thread replenishing mechanism in which thread is replenished on the bob-bin through a bobbin thread tensioning spring. This patented construction, however, is incorporated in a cyclically operated commercial sewing machine in which each successive sewing operation is identical so that the same length of bobbin thread is replenished each time and in which the position of sewing machine parts and the length of thread end from the eye of the needle at the start of bobbin thread replenishment may be regulated precisely and will always be the same. Consequently, in the United States Patent No. 3,063,392 it is feasible to provide means for positively clamping the starting needle thread end to the loop taker beak at the start of bobbin replenishment and to provide ancillary thread manipulating means similarly taking advantage of the uniform conditions of operation of the machine to effect introduction of the thread through the bobbin tensioning spring.

In operation of a household sewing machine or other general purpose sewing machine, however, the amount 3,407,760 Patented Oct. 29, 1968 ice of thread to be wound on the bobbin varies widely and the position of the parts and the length of needle thread extending from the needle eye at the start of bobbin replenishment cannot be predicted. Problems arise, therefore, in providing a thread winding mechanism which in a household sewing machine will reliably replenish bobbin thread through a bobbin threadtensioning spring.

In the present invention bobbin thread replenishment through a bobbin thread tensioning spring is effected with certainty and reliability of the provision of a novel and advantageous means for differentiating between needle thread manipulation during sewing and during bobbin thread replenishment. This invention also provides for a novel mode of engaging replenishment thread on the bobbin including provision for bobbin rotation during thread replenishment in a direction opposite that of loop taker movement. In addition, this invention provides for a novel mechanism for rotating the bobbin during thread replenishment which is advantageous not only in its compact interrelationship with the means :for differentially manipulating thread during bobbin thread replenishment, but also in that the winding mechanism becomes deactivated and remains stationary during sewing thus minimizing the power requirements of the machine.

With the above and additional objects and advantages in view as will hereinafter appear, this invention comprises the devices, combinations and arrangements of parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which:

FIG. 1 is a vertical cross-sectional view taken transversely across a sewing machine bed substantially through the axes of the loop taker shaft and of the control rock shaft and illustrating a loop taker to which the bobbin thread replenishing mechanism of this invention is applied,

FIG. 2 is a top plan view of the loop taker of FIG. 1 and a fragment of the bobbin thread replenishing mechanism illustrated at needle loop seizure with the parts in a position in which sewing will take place,

FIG. 3 is a top plan view of the loop taker similar to that of FIG. 2 but showing the position of parts in which bobbin thread replenishment will take place,

FIG. 4 is a vertical cross sectional view taken longitudinally along the sewing machine bed of FIG. 1 substantially through the axes of the loop taker shaft and of the control rock shaft,

FIG. 5 is a cross sectional view taken substantially along line 5--5 of FIG. 4 illustrating the control linkage for the bobbin driving mechanism in the position occupied during bobbin winding,

FIG. 6 is a cross sectional view similar to that of FIG. 5 but showing the control linkage in the position occupied during sewing,

FIGS. 7, 8, 9, and 10 are top plan views of the loop taker as shown in FIG. 3 with portions broken away and showing the position of parts and the thread at various successive stages during bobbin thread replenishment.

FIG. 11 is a top plan view of the loop taker as shown in FIG. 2 showing the position of parts and threads during manipulation of a needle thread loop wihle sewing.

FIG. 12 is a cross sectional view taken substantially along line 12-42 of FIG. 11,

FIGS. 13A, 13B and are fragmentary elevational views of the loop seizing beak portion of the loop taker at and after needle thread loop seizure with the parts arranged for sewing as illustrated in FIG. 2,

FIGS. 14A and 14B are fragmentary elevational views of the loop seizing beak portion of the loop taker at and after needle thread loop seizure with the parts arranged for bobbin thread replenishment as illustrated in FIG. 3,

FIG. 15 is an exploded perspective view of the loop 3 taker and bobbin winding mechanism of FIGS. 1 through 6.

FIG.16 is a vertical cross sectional view similar to that of FIG. 1 but illustrating a modified form of bottom thread replenishing mechanism,

FIG. 17 is a cross sectional view taken substantially along line 1717 of FIG. 16,

FIG. 18 is a cross sectional view taken substantially along line 18-18 of FIG. 17, and

FIG. 19 is a perspective view of the modified form of bobbin thread replenishing mechanism of FIG. 16.

In the drawings only a fragment of a sewing machine bed 21 is illustrated in the vicinity of a loop taker which is indicated generally at 22. A fragment of a thread carrying needle 23 and a presser foot 24 are also illustrated in FIGS. 1 and 4. Any conventional actuating mechanism may be employed for operatively interconnecting the needle and loop taker for movement in cooperative relation necessary for the formation of lock stitches. lreferably the needle is reciprocated endwise and the loop taker is rotated in timed relation therewith two revolutions during each reciprocation of the needle. The actuating mechanism interconnecting the needle and loop taker may take the form illustrated in the United States Patent No. 3,115,855 to which reference may be had Included as a portion of the actuating mechanism is a bed shaft 25 journaled in a bushing 26 in a web 27 depending beneath the bed 21 to which is fixed by a set screw 28 a bevel pinion 29 for driving the loop taker.

The bevel pinion 29 is disposed within an upwardly open loop taker cavity 30 formed in the bed 21 between the web 27 and cavity sidewalls 31. The cavity 30 is closed at the top by a throat plate 32 which is slotted as at 33 to accommodate a conventional feed dog 34 and which is formed with a needle aperture 35. A retractable slide cover plate 36, which abuts the threat plate when in closed position, also spans the loop taker accommodating cavity in the bed and when retracted the slide cover plate provides access to the loop taker.

Extending into the loop taker accommodating cavity 30 from the side wall 31 is a web of the sewing machine frame in which is supported the loop taker and control mechanism for rendering the loop taker effective selectively to replenish bobbin thread or to sew. A bushing 41 in the web 40 supports a flanged stud shaft 42 for turning movement in the web 40 with a shoulder 43 of the stud shaft engaging the bushing 41 to locate the stud shaft axially. Journaled for rotation about the stud shaft 42 is a bevel gear 44 formed with a counterbore 45 embracing an annular shoulder 46 formed on the stud shaft. The bevel gear 44 which is in mesh with the bevel pinion 29 has secured to it by screws 47 a cup-shaped upwardly open loop taker body portion 48. The loop taker body portion 48 may be formed as a sheet metal stamping and includes a fiat bottom portion 49 and a straight cylindrical side wall 50. The bottom. portion 49' of the loop taker body is apertured as at 51 to embrace the stud shaft 42 and to overlie the stud shaft shoulder 46 thus together with the pinion gear counterbore 45 restraining the loo taker axially of the stud shaft 42. The cylindrical side Wall of the loop taker body portion is formed with a plurality of spaced inwardly extending lugs 52 which are preferably struck inwardly from the side wall each at the same distance axially of the loop taker body portion from the bottom portion 49. The lugs 52 collectively define an inner bearing race for a bobbin case 53 which will be described in detail hereinbelow. The cylindrical side wall 50 of the loop taker body portion is also formed with a trapezoidal notch of which one acute angular portion 54 provides a camming surface for urging seized needle thread loops into a throat 55 into which thread loops seized by the loop taker gradually progress after loop seizure.

Seated upon the rim of the cylindrical side wall 50 is an annular loop taker beak ring which as illustrated in FIGS. 1, 4, and 15 is formed with an L-shaped cross section including a cylindrical limb 61 depending inside the cylindrical side wall 50 of the loop taker body portion and an annular limb 62 overlying the rim of the side wall of the loop taker body portion. The loop taker beak ring 60 is formed with a gap 63 and at one side of the gap the annular limb 62 is formed with a needle thread engaging beak 64. The annular limb 62 of the loop taker beak ring is also formed with an inwardly extending thread camming fin 65. Because of the gap 63 in the loop taker beak ring, it may be formed or sprung into a nominal diameter larger than that of the cylindrical side wall of the loop taker body portion and pressed into smaller overall diameter during insertion of the cylindrical limb 61 into the loop taker body portion. When the beak ring thus assembled is released, the cylindrical limb 61 will be urged outwardly tightly against the cylindrical side wall 50 of the loop taker body portion. while this frictional engagement may be sufiicient to lock the beak ring in place on the loop taker body portion one or more locking pins 66 set into the cylindrical side wall 50 and into apertures 67 in the beak ring 60 may be used positively to interlock the beak ring in place on the loop taker body portion with the gap 63 overlying the trapezoidal notch 54 in the side wall 50 of the loop taker body portion. The annular limb 62 of the loop taker beak ring is formed adjacent to the beak 64 with an outwardly extending shoulder 68 which serves as a thread stop to prevent a needle thread loop which is seized by the beak from slipping downwardly over the loop taker body portion.

The cylindrical limb 61 of the beak ring extends in spaced relation to the lugs 52 struck into the loop taker body portion and complements the lugs in providing an upper bearing surface constraining the bobbin case 53 rotatably within the loop taker body portion.

The bobbin case 53 is formed with a substantially cylindrical center portion 70 including an internal cylindrical bobbin accommodating cavity 71 of which the bottom wall is formed with an aperture 72. Extending outwardly from the central cylindrical portion 70 of the bobbin case is an annular bearing rib 73 which is formed with a gap 74 defining at one side indicated at 75 in the drawings a substantially radially extending shoulder adapted, as will be described in greater detail hereinbelow, to intercept and separate two limbs of a needle thread loop seized by the loop taker beak during sewing. The upper surface of the bearing rib 73 of the bobbin case is formed with spaced recesses 76 and 77, one on each side of a land portion 78 which land portion is disposed midway opposite the gap 74 in the bearing rib. Spanning both recesses 76 and 77 as well as the land portion 78 is a fiat leaf spring 79 which is semicircular in configuration generally conforming to the shape of and overlying the bearing rib. A fastening screw 80 secures the spring upon the bearing rib while a tension adjusting screw 81 threaded through the spring bears against the bearing rib in the recess 76 and serves to regulate the force with which the spring is biased against the land portion 78 thus to regulate the friction which will be applied by the spring to resist passage of thread between the spring and the land portion. The spring 79 is formed above the land 78 with a thread guiding notch 82 and ad jacent to the notch with an outwardly projecting finger 83 which enters a slot 84 in an upturned needle guarding lip 85 formed on the bobbin case to extend across the gap 74. Near the free extremity of the spring 79 a thread engaging ear 86 is formed to extend radially outward from the spring and the free extremity of the spring beyond the ear 86 is slightly upturned as at 87 for the purpose of facilitating the manual insertion of bobbin thread over the spring 79. Adjacent to the tension adjusting screw 81, the spring 79 is formed with a triangularly shaped projection 88 which is bent upwardly and formed with a sharpened thread cutting edge 89. As illustrated in FIGS. 2 and 15, the projection 88 is disposed closely adjacent to the central cylindrical portion 70 of the bobbin case and extends upwardly only to the level of the top of the central cylindrical portion of the bobbin case. As will be explained hereinbelow, this particular form and location of the thread cutting edge 89 will prevent it from engaging the sewing threads during sewing operations, but will engage and sever the beginning end of needle thread replenishment after the needle thread has been lodged in the bobbin.

On the upper face of the bobbin case hearing rib 73 an inclined ramp 90 is formed beyond the free extremity of the bobbin thread tensioning spring 79 which ramp terminates flush with the upper edge of the cylindrical portion 70 of the bobbin case and serves as an aid in directing needle thread into the bobbin at the start of bobbin thread replenishment. Additionally, the cylindrical center portion of the bobbin case is formed with a notch 91 beyond the ramp 90 for the dual purpose of facilitating removal of the bobbin and as will be described hereinbelow of aid ing in the manipulation of thread during bobbin replenishment. The bobbin which is indicated generally at 95 as best illustrated in FIG. is constructed so as to be positionable in the bobbin case cavity 71 with either face of the bobbin disposed upwardly. To this end the bobbin is formed with a first flange 96 provided with an inwardly tapered boss 97 and a short stud 98 formed integrally therewith. Both the outer face 99 of the first bobbin flange 96 and the free extremity of the stud 98 are formed with recessed slots 100 which are rectangular in shape and adapted as will be described hereinbelow to accommodate an element of the bobbin rotating mechanism during bobbin thread replenishment. The second flange 101 of the bobbin is formed with the same shape as the first flange 96 and includes a similar tapered boss 102, but in place of the stud 98 of the first flange 96 the second flange 101 is formed with an aperture snuggly accommodating the short stud 98. When the bobbin flanges are assembled as illustrated in FIG. 15, a metallic washer 103 is disposed on the stud 98 between the bobbin flange bosses 97, 102 and the bobbin flanges afiixed with respect to each other as with an adhesive. The washer 103 is formed with a plurality of evenly spaced peripheral notches 104 which serve to engage and secure to the bobbin a replenishment thread which is introduced to the bobbin.

Disposed inside the hook body and beneath the bobbin case is a bobbin case rotation restraining plate 105 which is formed with a central aperture 106 seated on an annular raised boss 107 surrounding the upper extremity of a bore 108 formed lengthwise through the stud shaft 42. Clearance holes 109 in the rotation restraining plate 105 accommodate fastening screws 110 which are threaded into the stud shaft 42 securing the rotation restraining plate rigidly to the stud shaft. The rotation restraining plate is formed at one side with a raised lip 1'11 which is disposed in the gap 74 of the bobbin case bearing rib 73 thereby to control the angular position of the bobbin case within the hook body. The rotation restraining plate 105 radially inwardly of the raised lip 111 is formed with an arcuate needle clearance slot 112.

With particular reference to FIGS. 1, 5 and 15, the bobbin winding mechanism and the mechanism for controlling transition from sewing to bobbin thread replenishment and vice versa will now be described. Journaled loosely in the bore 108 of the stud shaft 42 which capacity for endwise movement therein is a bobbin winding shaft 120. The central aperture 51 in the hook body, the aperture 106 in the bobbin case rotation restraining plate, and the aperture 72 in the bobbin case provide a clear path for axial movement of the bobbin winding shaft toward and away from the bobbin in the bobbin case cavity 71. The upper extremity of the bobbin winding shaft is formed with a transverse slot 121 in which a sliding tang 122 is disposed. A keeper pin 123 fitted into the bobbin winding shaft across the slot 121 extends through an elongated slot 124 in the tang 122 to limit upward movement of the tang in response to the force applied to it by a coil spring 125 constrained in a blind axial bore 126 in the bobbin winding shaft 120. Fast on the lower extremity of the bobbin winding shaft 120 is a disc 127' formed on each face with a tapered central hub portion 128. As illustrated in FIG. 4 the periphery of the disc 127 is adapted to abut a driving ring 129 preferably of flexible material such as hard rubber which is carried on the hub 130 of the loop taker driving pinion 29 on the bed shaft 25.

For controlling selectively the operation of the aforementioned bob'bin winding shaft as well as other aspects of the transition between sewing and winding condition of the parts, a control rock shaft is journaled in a bushing 141 which is secured as by a setscrew 142 in the web 40 of the sewing machine frame. The bushing 141 protrudes from the web upwardly into the loop taker cavity 30 and is slabbed as at 143 and formed at the upper extremity with a shoulder portion 144 so as to accommodate nonrotatably thereon an angle bracket 145 to which a latch lever 147 is fulcrumed by means of a shoulder screw 146. The latch lever is for-med with a latch lug 148 and with a latch operating upper extremity 149.

Secured to the top of the control rock shaft 140 by a setscrew 150 is the hub portion 151 of a control arm 152, which control arm is disposed as illustrated in FIGS. 1 and 4 slightly below the level of the underside of the slide cover plate 36. Beneath the free extremity of the control arm is fixed a spacer plate 153 and a thread engaging plate 154 which extends radially inwardly from the spacer plate toward the control rock shaft and in a spaced relation to the control arm 152 equal to the thickness of the spacer plate. The inner edge of the thread engaging plate 154 forms at one side of the control arm an obtuse angular corner 155 while at the opposite side presents a laterally extending finger 156. The hub 151 of the control arm is formed with a pair of latch seat notches 157, 158 which cooperate with the latch lug 148 to detain the control arm 152 in two positions with respect to the loop taker. When the latch lug 148 is seated in the latch seat notch 157, the cont-r01 arm 152 will occupy the position illustrated in full lines in FIG. 3 and indicated by the line marked W in FIG. 3 in which position the parts will perform the winding or bobbin thread replenishing operation. When the latch lug is seated in the notch 158 the control arm 152 will occupy the position illustrated in FIG. 2 and indicated by the line marked S in FIGS. 2 and 3 in which position the parts will be set for normal lock stitch sewing operations.

Beneath the web 40 of the sewing machine frame the control rock shaft 140 has secured thereto as by a setscrew 160 a compound lever 161 including an upper arm 162 of which the extremity 163 overlies the disc 127. A lower arm 164 of the compound lever is formed with a curved free extremity 165 which extends beneath the disc 127. A coil spring 166 attached to the lower arm. .164 is anchored on a bracket 167 on the sewing machine frame and serves to bias the compound lever and with it the control rock shaft and control arm 152 toward the sewing position as illustrated in FIG. 2. A pin 168 fixed on the upper arm 162 of the compound lever is embraced by the bifurcated extremity 169 of a lever 170 which is apertured as at 171 to set upon a boss 172 depending beneath the stud shaft 42. The lever 170 is fixedly secured to the stud shaft 42 by means of a fastening screw 173 threaded into the lStlld shaft.

Operation In the operation of a sewing machine fitted with the mechanism of this invention as described above, the nature of the operation of the stitch forming instrumentalities, whether lock stitches will be produced or whether the bobbin thread will be replenished, is controlled by the machine operator and particularly by the position in which the machine operator sets the control arm 152. Two possible positions of the control arm 152 have been described hereinabove, i.e., the full line position illustrated in FIG. 2 as determined by the setting of the latch lug-148 in the notch 158 in which the machine parts will be set for sewing; and the full line position of the parts as illustrated in FIG. 3 as determined by the setting of the latch lug 148 in the notch 157 in which the parts will occupy a position in which the bobbin thread will be replenished. In addition to these two possible positions of the control arm 152, there is illustrated in dotted lines in FIG. 3 a third possible position of the control arm indicated by a line Z in which the control arm is located by a stop arm 180 pivotally secured on a fulcrum stud 181 carried in the machine frame. Since the control arm 152 and the stud shaft 42 will be interconnected by way of a lever 170, the pin 168, and the compound lever 161, angular adjustment of the position of the control arm 152 results in a corresponding angular adjustment of the position in which the bobbin case is restrained from rotation with the loop taker. FIGS. 2 and 3 illustrate the relationship between the angular position of the bobbin thread guiding notch 82 in the bobbin thread tensioning spring 79 with respect to the angular position of the adjustment of the control arm 152. Whereas in FIGS. 2 and 3 the various positions of the control arm 152 are indicated by the lines marked S, Z, and W the corresponding positions of the bobbin thread guiding notch 82 are indicated by the lines marked S, Z, and W. In the position of the control arm 152 illustrated in FIG. 2 and indicated by the line marked S the bobbin thread guiding notch 82 is located to one side of the path of needle reciprocation and provides a highly desirable bobbin thread lead for straight stitching operations because the needle will always be reciprocated on the same side of the bobbin thread, and therefore, each successive stitch will be formed in like manner and the periodic formation of half-hitched stitches will be minimized. The position of the control arm 152 as indicated by the line marked Z which is established by manual turning of the stop arm 180 into effective position as illustrated in dotted lines in FIG. 3, will position the bobbin thread guiding notch 82 substantially into alignment with the central position of needle reciprocation of a zigzag needle. With this adjustment the lead of the bobbin thread will be substantially uniform as between needle penetrations in either the extreme left-hand or right-hand stitches of a zigzag pattern and by this means favorable balance will be provided between the stitches of a zigzag arrangement. In either of the two positions of the control arm marked S or Z in FIGS. 2 and 3 the compound lever 161 will not shift the bobbin winding shaft 120 into engagement with the bobbin nor the disc 127 into driven engagement with the driving ring 129. There is an additional position which it is possible for the operator to position the control arm 152 which is not illustrated in FIGS. 2 or 3, which is the position in which the spring 166 will bias the control arm 152 when the latch lever 149 is released to draw the latch lug 148 from the latch notch 158. In this position the control arm 152 will move an additional increment radially outwardly of the loop taker and expose the bobbin 95 completely so that the bobbin may be removed as for repair or replacement. The last described position of the control arm 152 has not been illustrated since such position is not one in which the mechanism should be operated either for sewing or bobbin thread replenishment.

When the control arm 152 is shifted into the position indicated by the line marked W in FIG. 3 three distinct changes occur in the relationship of the parts so that the next succeeding loop of needle thread which is engaged by the beak of the loop taker 'will be introduced to the bobbin and wound thereon to replenish the supply of bobbin thread. Firstly, as mentioned above the bobbin case will be shifted angularly by the shift in angular po* sition of the rotation restraining plate 105. With respect to the path of reciprocation of the needle 23 such shift of the bobbin case position will not only bring the bobbin thread guiding notch 32 to the opposite side of the path of needle reciprocation as illustrated in FIG. 3 but it will also shift the shoulder 75 formed on the bobbin case bearing rib closely adjacent to the path of needle reciprocation. In this position of the shoulder the next succeeding needle thread loop seized by the loop taker beak will be manipulated in a manner completely different from that in which it is handled during normal stitch forming operation.

Secondly, the lower arm 164 of the compound lever 161 will be shifted beneath the tapered central hub portion 128 below the disc .127 and will serve to elevate the disc 127 into engagement with the driving ring 129 and elevate the sliding tang 122 into engagement with the underside of the bobbin so that the tang will seat in the bobbin notch as soon as the bobbin winding shaft has turned it sufficiently to align the tang with the notch. It is pointed out that since the disc 127 engages the driving ring 129 at the opposite side of the gear 29 from the point from which the gear meshes with the loop taker gear 44 the bobbin will be rotated during bobbin thread replenishment in a direction opposite that of rotation of the loop taker.

Thirdly, the thread engaging plate 154 beneath the control arm 152 in the position of the control arm indicated by the line marked W in FIG. 3 assumes an omrative position in which it can engage the upper most limb of needle thread loop being manipulated by the lOOp taker. The thread engaging plate 154 can engage a limb of the seized needle thread loop in this position of the control arm not only because the obtuse angular corner 155 makes the initial contact of the thread engaging plate with the needle thread limb but also because elevation of the bobbin winding shaft 120 will serve to raise the bobbin 95 into engagement with the thread engaging plate 154 as is illustrated in FIG. 4. As a result, the thread cannot pass beneath the thread engaging plate 154 and will enter between the thread engaging plate and the control arm 152 and will be drawn against the spacer plate 153.

In considering the result of the above-mentioned changes in the relationship of the parts which occurs when the control arm is shifted into the position for replenishing thread, reference is first directed to FIGS. 13A, 13B, and 13C, and 14A, and 14B which illustrate the differences in the manner in which the loop taker manipulates a seized loop of needle thread during normal sewing operation as compared with the manipulation of the thread during bobbin replenishing operations. FIGS. 13A, 13B, and 13C illustrate the typical relationship between the path of needle reciprocation and the shoulder 75 on the bobbin case hearing rib 73 during sewing .and these figures illustrate that during sewing, the seized needle thread loop will have been drawn completely into the throat 55 of the notch 54 in the loop taker body portion prior to movement of the throat to a position opposite the shoulder 75. As a result, the seized needle thread loop will be .detained against the shoulder 75 and the needle thread loop will thereafter be manipulated one limb beneath the bobbin case and the other limb over the bobbin case. FIG. l1 illustrates a top plan view of the loop taker with the loop taker beak in a position approximately degrees beyond loop seizure and illustrates the manner in which the division of the seized needle thread loop by the shoulder 75 results in the expansron and manipulation of the loop completely about the bobbin case. FIG. 11 also illustrates the angular relation which will obtain as between the uppermost limb of the needle thread loop during sewing and the thread engaging plate 154 on the control arm 152. The needle thread as illustrated in FIG. 11 will first move opposite to the thread engaging plate 154 at a point outwardly beyond the obtuse angle 155 and will thus not be engaged by the plate. An additional reason why the needle thread loop during sewing will not be engaged by the thread engaging plate 154 is that the bobbin will not be elevated by the bobbin winding shaft during sewing.

Referring to FIGS. 14A and 14B, the shoulder 75 on the bobbin case bearing rib 73 during bobbin thread replenishment will be shifted closely adjacent to the path of needle reciprocation and as illustrated in FIG. 14B

the seized needle thread loop will not have reached the throat 55 before the throat will be closed by rotation beyond the shoulder 75. As .a consequence, both limbs of the needle thread loop will be carried by the loop taker beak above the bobbin case hearing rib 73. FIG. 7 illustrates the position of rotation of the loop taker at the start of bobbin thread replenishment when the seized thread loop has been carried with both limbs above the level of the bobbin case bearing rib 73. That limb of the seized needle thread loop which extends beneath the hook bead ring 60 is indicated in FIGS. 7, 8, 9, and as N and is shown in FIG. 7 as being carried into engagement with the car 86 on the bobbin tensioning spring 79. The other limb of the thread is indicated as N FIG. 8 illustrates the position of parts after the loop taker has been rotated approximately 90 degrees beyond that illustrated in FIG. 7 and illustrates the engagement of the upper limb of the seized needle thread loop N between the thread engaging plate 154 and the control arm 152.In FIG. 8 the lower limb of the needle thread N is illustrated as being drawn beneath the free extremity of the bobbin thread tensioning spring '79 and additionally being drawn up the ramp 90 toward the bobbin. FIG. 9 illustrates the position of parts after the loop taker has been rotated approximately 90 degrees beyond that illustrated in FIG. 8 and shows the lower limb N of the seized needle thread loop drawn into the bobbin and across the washer 103 thence to the thread cutting edge 89 of the projection 88 on the bobbin thread tensioning spring, while ,the upper limb of the seized needle thread loop N, is snubbed about the spacer plate 153 on the control arm. The lower limb N of the needle thread loop will pass into one of the peripheral notches 104 of the washer 103 by virtue of the angular lead of these limbs of thread across the bobbin. the angular lead of the thread limb N is occasioned since at one side of the bobbin the thread will pass over the rim of the central cylindrical portion 70 of the bobbin case while at the opposite side this thread limb will drop through the notch 91 of the bobbin case.

Since the limb N of the needle thread loop introduced to the bobbin will seat in one of the notches 104 of the washer 103, when the bobbin rotation is initiated by the bobbin winder shaft 120 in a direction opposite that of the rotation of the loop taker, the thread limb N caught in the washer notch will be wound upon the bobbin as illustrated in the FIG. 10 and the tension on the thread passing over the thread cutting edge 89 will increase sharply so that the thread will be cut and winding of the single limb of thread on the bobbin can then proceed.

The direction of the rotation of the bobbin opposite that of the loop taker will draw the thread as it is wound on the bobbin almost immediately into the notch 82 in the bobbin thread tensioning spring 79. As a result, even if only an extremely short length of bobbin thread is wound, when the parts are reverted into sewing position, the bobbin thread will be properly introduced to the bobbin thread guiding notch 82.

Illustrated in FIGS. 16 to 19 is a modified form of bobbin winding mechanism and associated controls. As shown in FIG. 16, the sewing machine frame, the loop taker 22, its support and drive arrangement, and the control arm 152 remain identical in construction and operation as in the form of construction described heretofore.

In the modified form of construction, a bobbin winding shaft 200 which is journaled in the bore 108 of the stud shaft 42 has a bobbin engaging drive lug 201 formed integrally on the upper extremity and has fast on the lower extremity a bevel pinion 202 which is adapted upon axial shift of the bobbin winding shaft 200 to engage and disengage in meshing relation with the loop taker driving pinion 29. The bevel pinion 202 together with a collar 203 is secured on the bobbin Winding shaft 200 by a set screw 204. The collar 203 is formed with an annular groove 205 beneath the pinion 202. In the modi- 10 fied form of construction illustrated in FIGS. 16 through 19, the interconnection between the control rock shaft 140 and the stud shaft 42 differs from that described hereinabove as does the means for raising and lowering the bobbin winding shaft in response to angular shift of the control arm 152.

Carried on the boss 172 beneath the stud shaft 42 and secured thereon by a fastening screw 206 is a lever 207 formed with three radial fingers 208, 209, and 210 of which the center finger 209 is notched as at 211 to accommodate one extremity of a coil spring 212. The radial fingers 208, 209, and 210 serve after the fashion of gear teeth and mesh with a pair of fingers 213, and 214 formed on a lever 215 which is made fast on the control rock shaft 140 by a set screw 216. The lever 215 is formed with a notch 217 in which is hooked a coil spring 218 which is anchored on the machine frame in a manner similar to that of the spring 166 of the form of construction illustrated in FIG. 4. The spring 218 serves to bias the control arm 152 toward the sewing position.

By virtue of the fingers 208, 209, 210 in meshing relation with the fingers 213, and 214, angular shift of the control arm 152 will influence corresponding angular adjustment of the stud shaft 42 and to the bobbin case rotation restraining plate 105 secured thereto.

For influencing axial shift of the bobbin winding shaft 200 in response to angular shift of the control arm 152, an operating lever 220 is retained loosely by a fastening screw 221 to a shoulder 222 projecting beneath the control rock shaft 140 so that the shoulder 222 provides a fulcrum for the operating lever. Between the shafts 42 and 140, the operating lever 220 is formed with a semicircular slot 223 accommodating the lower end of the coil spring 212. Constrained within the coils of the spring 212 is a pin 224 hearing at the top against the finger 209 and hearing at the bottom against the operating lever 220. At the opposite extremity from the fulcrum, the operating lever 220 is bifurcated as at 225 and embraces the annular groove 205 in the collar 203 fast on the bobbin winding shaft 200.

As illustrated in solid lines in FIGS. 17 and 18, when the control arm and control rock shaft 140 are turned so as to swing the finger 209 directly over the operating lever 220, the pin 224 will be positioned substantially parallel to the shafts 42 and 140 and will force the operating lever 220 downwardly a maximum distance, equivalent to the length of the pin 224, from the finger 209 and will force the bobbin winding shaft 200 downwardly carrying the drive lug 201 out of engagement with the bobbin slot and shift the bevel pinion 202 on the bobbin winding shaft out of meshing relation with the drive pinion 29.

As illustrated in dashed line's in FIGS. 17 and 18, wheri the finger 209 is swung to one side of the operating lever 220, the pin 224 Will be shifted into an angular relation with the axes of the shafts 42 and 140 and in toggle-like fashion the spring 212 will urge the bobbin winding shaft upwardly bringing the drive lug 201 into engagement with the bobbin and bringing the pinions 202 and 29 into meshing relation.

In the operation of the modification illustrated in FIGS. 16 to 19, the same angular relationships between the control arm 152 and the bobbin case rotation restraining plate apply as are illustrated in FIGS. 2 and 3 and as are described hereinabove. Similarly, the manipulation of threads both during sewing and during bobbin thread replenishment obtain as were described with regard to the construction illustrated in FIGS. 1 to 15.

In the construction illustrated in FIGS. 16 to 19, since the pinions 29 and 202 occupy meshing relation over a range of axial positions of the bobbin winding shaft 200, the need for a sliding bobbin driving tang 122 is obviated. Moreover, the pinions 29 and 202 when in meshing relation, react in a different manner to an impending overwind of the bobbin than do the disc 127 and the driving ring 129. Whereas, the friction drive 127 and 129 can slip when overwinding of the bobbin increases the resistance to be overcome by the drive, the pinions 29 and 202 develop components of force applied axially of the bobbin winding shaft which although of small magnitude will cause depression of the bobbin winding shaft when an overwinding condition arises. Not only does this result in cessation of further attempts to wind thread on the bobbin, but it also produces an audible signal indicating the fully wound condition of the bobbin.

Having thus set forth the nature of this invention, what is claimed herein is:

1. A bobbin thread replenishing mechanism for a sewing machine having a circularly moving loop taker, a bobbin case having a bearing rib formed with a gap, a bobbin carried in said bobbin case, a raceway provided in said loop taker for said bobbin case bearing rib, said raceway formed with a gap, a loop seizing beak carried on said loop taker in said raceway gap and at one side of said raceway, said loop taker being provided with thread loop manipulating surface extending from said loop seizing beak and terminating in a throat disposed at the opposite side of said raceway, and means for constraining said bobbin case from circular movement with said loop taker with said bobbin case bearing rib gap and said loop taker raceway gap open to each other during loop seizure by said loop seizing beak, means for selectively influencing the position of the seized thread loop along said thread loop manipulating surface at the moment of overlap of said gaps causing said loop taker to manipulate the seized thread loop completely about said bobbin case for the formation of lock stitches when said thread loop is positioned on that side of said raceway occupied by said throat at overlap of said gaps, and causing said loop taker to manipulate the seized thread loop entirely across one side of said bobbin case and onto said bobbin when said thread loop is positioned on that side of said raceway occupied by said beak at overlap of said gaps.

2. A bobbin thread replenishing mechanism as set forth in claim 1 in which said means for selectively influencing the position of the seized thread loop along said thread loop manipulating surface at the moment of overlap of said gaps comprises means for providing movement of said seized thread loop along said thread loop manipulating in direct proportion to the angular movement of said loop taker beyond loop seizure, and means for selectively varying the angular interval between loop seizure by said beak and overlap of said gaps.

3. A bobbin thread replenishing mechanism as set forth in claim 2 in which said means for selectively varying the angular interval between loop seizure by said beak and overlap of said gaps comprises operator influenced means for repositioning said means for constraining the bobbin case from circular movement with said loop taker.

4. A bobbin thread replenishing mechanism as set forth in claim 1 in which a bobbin thread tensioning spring means is carried by said bobbin case and bears against said bobbin case frictionally to resist passage of bobbin thread therebetween, said bobbin thread tensioning spring being formed with a free extremity disposed across the path of said thread loop manipulated entirely across one side of said bobbin case and onto said bobbin so as to direct between said bobbin thread tensioning spring and said bobbin case only those thread loops being manipulated onto said bobbin.

5. A bobbin thread replenishing mechanism as set forth in claim 1 in which a thread cutting blade is carried by said bobbin case and disposed across the path of said thread loop manipulated onto said bobbin and extending from said bobbin to said loop taker thread manipulating surface.

'6. A bobbin thread replenishing mechanism as set forth in claim 4 in which a thread cutting blade is carried by said bobbin thread tensioning spring at substantially the diametrically opposite side of said bobbin case from said free extremity of said bobbin thread tensioning spring, and in which said thread cutting blade is disposed across the path of said thread loop manipulated onto said bobbin and extending from said bobbin to said loop taker thread manipulating surface.

7. A bobbin thread replenishing mechanism as set forth in claim 6 in which said bobbin thread tensioning spring comprises a semicircular flat leaf spring secured to said bobbin case bearing rib and in which said thread cutting blade is struck up from said flat leaf spring.

8. A bobbin thread replenishing mechanism for a lock stitch sewing machine having a rotary loop taker, means for imparting rotary movement to said loop taker in one direction, a bobbin case journaled in said loop taker, means for restraining said bobbin case from rotation with said loop taker, a bobbin journaled in said bobbin case, and means providing for passage about said bobbin case of thread loops seized and being manipulated by said loop taker during conventional lock stitch formation, said bobbin thread replenishing mechanism including means for winding a thread on said bobbin in place in said bobbin case comprising means for at will introducing at least one limb of a thread loop seized by said loop taker into said bobbin during rotation of said loop taker, thread engaging means carried by said bobbin for securing said introduced thread limb to said bobbin, and means for rotating said bobbin in a direction opposite that of said loop taker.

9. A bobbin thread replenishing mechanism as set forth in claim 8 including an actuating element journaled for rotation about an axis carried in said sewing machine, and means operatively connected to said actuating element at diametrically opposite sides of the axes thereof for driving said loop taker and said bobbin in opposite directions of rotation.

10. A bobbin thread replenishing mechanism as set forth in claim 8 in which a driven gear is fast on said loop taker, a driving gear journaled in said sewing machine is disposed in mesh with said driven gear, and said means for rotating said bobbin comprises a bobbin driving shaft journaled telescopically relatively to said driven gear, driven means fast on said bobbin driving shaft, and driving means associated with said driving gear and operatively engageable with said driven means on the side of said driving gear which is diametrically opposite that in mesh with said driven gear.

11. A bobbin thread replenishing mechanism as set forth in claim 10 in which said driven gear fast on said loop taker and said driving gear comprise meshing bevel gears arranged on substantially mutually perpendicular axes, and in which the driven means on said bobbin driving shaft comprises a bevel gear disposed to mesh with said driving gear at the side thereof diametrically opposite the loop taker driving gear.

12. A bobbin thread replenishing mechanism for a lock stitch sewing machine having a loop taker, a bobbin case journaled in said loop taker, means for restraining said bobbin case from rotation with said loop taker, and a bobbin journaled in said bobbin case, said bobbin thread replenishing mechanism comprising an operator p'osition able control member shifta'bly supported on said sewing machine, thread manipulating means influenced by a first operator influenced position of said control member to direct a thread loop from said loop taker about the bobbin case in the formation of lock stitches and in a second operator influenced position of said sewing machine to direct a thread loop from said loop taker onto said bobbin for bobbin thread replenishment, a bobbin rotating member associated with said loop taker, means for shifting said bobbin rotating member into and out of operative engagement with said bobbin, separable driving means for said bobbin rotating member, means effective in said first operator influenced position of said control member for separating said separable driving means for said bobbin rotation member, and means operatively connected to said operator positionable control member and effective in said 13 second operator influenced position thereof simultaneously to shift said bobbin rotating member into operative engagement with said bobbin and effect engagement of said driving means for said bobbin rotating member.

13. A bobbin thread replenishing mechanism as set forth in claim 12 in which said thread manipulating means comprises a shiftable bobbin case rotation restraining means, and in which said bobbin rotating member comprises an axially shiftable bobbin drive shaft journaled telescopically relatively to said loop taker, a driven member fast on said bobbin drive shaft and a drive member carried by said sewing machine for operative engagement by said driven member upon axial shift of said bobbin drive shaft, and in which the means operatively connecting said operator positionable control member to said thread manipulating means and to said bobbin rotating member comprises linkage connected to said control memher and effective simultaneously to shift said bobbin case 14 rotation restraining means and to move said bobbin drive shaft axially.

14. A bobbin thread replenishing mechanism as set forth in claim 12 in which said operator positionable control member comprises a control arm pivotally supported in said sewing machine adjacent to said loop taker, said control arm disposed substantially radially of said loop taker in said second operator influenced position thereof, and thread engaging means on said control arm effective only in said second operator influenced position thereof.

References Cited UNITED STATES PATENTS 3,106,176 10/1963 Doerner 112-181 X 3,115,855 12/1963 Ketterer 112-184 3,154,035 10/1964 Edwards 112--184 HERBERT F. ROSS, Primary Examiner. 

